The proposed research attacks the problem of plasma skimming in vascular networks with experiments using in vitro replicas of two bifurcation networks (branch diameter 10 to 50 Mum) perfused with red cell suspensions. Measurements of red cell velocity and red cell flux can be accomplished by the fluorescent labelling technique of Sorelius and Duling (1982). Measurements of volumetric fluorates and red cell flux will come from collection of effuent from each branch of the network replica. The data and analysis from this work will help in vivo microcirulationists interpret their results on network blood flow. The data obtained is applicable to the physiological problems of blood flow regulation and 02 delivery. More realistic computer network models can be developed from the anticipated data. The value of computer models is the simulation experiments they can perform, which cannot be done in vivo, in vascular disease research. These types of simulation experiments have application in hypertension and diabetes.